At Fri, 1 Apr 2011 11:05:35 +0100 CentOS mailing list <centos@xxxxxxxxxx> wrote:
>
> The reason for the udev hotplug rule is simply for the purpose of mounting removable devices as read-only. If udev is left to its devices, everything plugged up is read-write which is verboten in this application. Unfortunately, there seems to be no way (i've found) to distinguish, at device/bus level, between a system HDD, a hardware RAID volume and an eSATA device and handle the eSATA device uniquely from others. All eSATA and USB devices _must_ mount read-only. If everything is lined up at boot, sda and sdb are camped via fstab and udev deals with sdc and above, mounting what are known to be removable devices as r/o. Shotgun, i know, but there is no way of knowing in advance what devices the system (er, appliance) will see.
>
> tangled, huh?
Does this give you a clue (this is a rule I use for my thumb drive,
which is a vfat file system, and thus cannot have a LABEL'd file system):
gollum.deepsoft.com% cat /etc/udev/rules.d/10-local.rules
KERNEL=="sd[a-z]*", BUS=="scsi", SYSFS{device/vendor}=="Kingston", NAME="thumb"
Hint: the 'brand' of thumb drive I have is Kingston and == can be
replaced with !=.
In your special mount read-only hot plug rule, you just need a
SYSFS{device/vendor}!="3ware" (or whatever the vendor of the RAID array
shows up as -- look in /sys/block/sd<mumble>/device/vendor)
>
> thanks
>
> - csawyer
>
> Robert Heller heller at deepsoft.com
> Thu Mar 31 14:20:55 EDT 2011
>
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> At Thu, 31 Mar 2011 18:23:00 +0100 CentOS mailing list <centos at centos.org> wrote:
>
> >
> > thanks for the reply, Phil
> >
> > It would, were udev not inserting USB and/or eSATA drives at /dev/sdb1
> > and/or /dev/sdc1 and exposing the array to the udev rule intended to
> > handle only removable devices (at sdc or sdd). The array then mounts
> > unpredictably in /media/xxx-sdc1 or sdd1 - not what is wanted - depend
> > on how many removable devices are plugged at the time of rebooting. Of
> > course, a single removable device will camp at sdb, which is out of
> > reach of udev so the whole hotplug thing is broken until someone removes
> > all of the devices at site, allowing a clean boot.
>
> Do you have some *nonstandard* udev rule for hot plug devices? The
> *standard* hotplug udev rules are not tied to specific ranges of sdXX's
> -- my IDE-based laptop will properly handle a hot plugged USB device at
> /dev/sda for example.
>
> The hot plug logic should also not mess with not hot pluged devices. If
> your RAID array is mounted in /etc/fstab (or has a 'noauto' line in
> /etc/fstab with the idea of mounting it manually later or has something
> in automount's config for automounting it), the hot plug system should
> not touch it, no matter what /dev/sdXX it happens to land at, so long as
> you are using volume labels or some such to reference the mountable
> volumes.
>
> - cal sawyer
> Â
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--
Robert Heller -- 978-544-6933 / heller@xxxxxxxxxxxx
Deepwoods Software -- http://www.deepsoft.com/
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